The present invention relates to hydraulic pressure regulating valves.
Pressure regulating valves are used for example in hydraulic controls of automatic transmissions of motor vehicles. Their objective is to control transmission components such as for example couplings and to regulate their pressures.
A hydraulic pressure regulating valve is disclosed for example in the German patent document DE 43 24 748 A1. This pressure regulating valve is composed of a magnetic part and a valve flange which is anchored on it. The magnetic part includes an electrically controllable coil, a coil core and a movably guided armature which is held by a spring in the base position. The armature actuates a piston which is guided movably in the valve flange and which for regulation of the pressure releases or closes pressure medium connections between passages. The valve flange is sealed from the magnetic part by a diaphragm element. The latter is ring-shaped and fixed with its outer periphery on the valve body and with its inner periphery on the piston. The diaphragm element thereby follows the movement of the piston. In order to avoid a pressure buildup in an inner chamber of the diaphragm element, the rubber chamber is connected with the return of the pressure regulating valve.
The armature movement of the pressure regulating valve is performed undampened. Thereby the pressure regulating valve is relatively sensitive to mechanical vibrations of the magnetic circuit or pressure fluctuations of the pressure regulating circuit. For many applications such undampened regulating condition is undesirable. In known pressure regulating valves, a dampening of the stroke movement of the piston can be performed with the use of separate dampening devices, for example a so-called spring accumulator. Such dampening devices have the disadvantages of their large mounting space, unfavorable dynamics, and relatively high costs.
It is also known to dampen the stroke movement of the piston in a pressure regulating valve via so-called gap dampening in the magnetic part. For this purpose the magnetic part, in contrast to the solution disclosed in the German reference DE 43 24 748 A1, is filled with pressure medium. The gap between the armature and the wall of the armature chamber and/or throttling openings in the armature form throttling elements for dampening of the medium stream which is displaced by the armature during its movement and thereby also the piston movement. A substantial disadvantage of the dampening of this type is on the one hand its dependence on the filling degree of the armature chamber with pressure medium, and on the other hand its temperature dependence because of the laminar stream which is formed in the relatively long throttle gaps. A further problem resides in entrainment of dust particles into the armature chamber which is filled with a pressure medium. These impurities negatively influence the magnetic characteristics of the pressure regulating valve, can cause wear of the components of the magnet parts or can deposit in the dampening gaps.
Accordingly, it is an object of the present invention to provide a hydraulic pressure regulating valve, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent herein after, one feature of the present invention resides, briefly stated, in a pressure regulating valve has a magnetic part which includes an electrically controllable coil, a coil core and a movable armature; a valve flange which is anchored on said magnetic part and has pressure medium guiding passages; a piston controlling a pressure in a passage connected to a consumer, said piston being loaded with said armature and controlling pressure medium connections between said passages; a diaphragm element which seals said valve flange relative to said magnetic part; means forming a return passage, said diaphragm element having at least one pressure chamber which is hydraulically connected with said return passage; and a throttling device formed so that said pressure chamber is connected with said return passage through said throttling device.
When the pressure regulating valve is designed in accordance with the present invention, a dampening device is integrated in the pressure regulating valve and does not change significantly the mounting volume of the valve and also does not require any filling of the magnetic part with pressure medium. The risk of emptying of the armature chamber, for example during transportation of the pressure regulating valve to consumers, is thereby prevented, and also a possible dirtying of the armature chamber during the operational time. In addition the required structural features of the components are manufactured in cost-favorable manner.
In accordance with the present invention it is especially advantageous when the guidance of a piston in the valve flange for forming of the damping device is utilized. This throttle device can be easily adjusted to corresponding requirements of the applications for the pressure regulating valve, by varying the gap dimension or the piston guide with recesses of different geometries and/or dimensions.
In an advantageous further embodiment of the invention, the magnetic part is formed as a proportional magnet, in which the armature is inserted at least partially into the interior of the magnetic core. Pressure regulating proportional magnetic valves have a very exact and accurate control of nominal pressure values, without requiring an expensive pressure regulating circuit. Thereby such pressure regulating valves are especially suitable for applications in of mass production, such as for example in the automobile industry.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.